On November 5, 2009, Komatsu America Corp. (KAC) introduced its newest “Green Machine,” the Hybrid PC200LC-8 excavator, into the North American market. This introduction took place at the company’s Cartersville, GA training center. Dave Grzelak, chairman and CEO of KAC, took great pride in introducing the newest addition to the Komatsu line of excavators. Before getting into the company’s history of “greening” its products, Grezlak introduced the Matt Santini, Mayor of Cartersville.
Grzelak gave attendees an overview of the company’s involvement with hybrid technology and its efforts to make its products more environmentally friendly. Two years ago Komatsu introduced the Sigmadozer blade for the D155 and D275 dozers that increases productivity while fuel efficiency by more than 10%; it also introduced large capacity wheel loaders with larger torque convertors that improved fuel efficiency more than 10%. Komatsu also produces notably efficient thermoelectric modules that can waste heat into electricity and high performance wire saws use to precision cut the silicon wafers that are used to make solar cells. The company also produces diesel electric off highway haul trucks that have haulage capacities of 300 tons.
In 2007 Komatsu introduced a hybrid forklift that uses a similar regenerative electrical energy system via capacitors. There are more than 400 of these currently operating in Japan. These forklifts achieve a 20% reduction in energy use compared to the standard electric powered models.
Grzelak pointed out that the CO2 reducing actions of a Hybrid PC200LC-8 operating 2,000 hrs per year emits 25 tons less than the conventional PC200LC-8. This is equivalent to 591 x 5,000 gallon tanker trucks.
Substantial “green” impact
Komatsu’s goal is to meet increasing global environmental concerns through the development of innovative equipment designed to reduce environmental impact, including CO2 reduction. By developing a successful hybrid excavator in the largest construction machine segment (20-22 ton), Komatsu’s green technology will have a substantial impact on saving fuel and reducing green house emissions.
“Komatsu’s decision to apply its engineering excellence to the largest construction machine segment, clearly signals our commitment to developing environment-friendly equipment”, Grzelak says. “Since the company’s inception, Komatsu has been setting the global standard for technology and engineering excellence and today that tradition continues with the introduction of the Hybrid PC200LC-8 excavator.”
Powered by the Komatsu Hybrid System, the Hybrid PC200LC-8 uses a newly developed electric swing motor, power generator motor, capacitor and diesel engine. Komatsu developed its revolutionary hybrid system to work on the principle of swing energy regeneration and energy storage using the Komatsu Ultra Capacitor system. Komatsu’s Ultra Capacitors provide fast energy storage and instantaneous power transmission.
The kinetic energy generated during the swing-braking phase is converted to electricity, which is sent through an inverter and then captured by the Ultra Capacitor. This captured energy is then discharged very quickly for upper structure rotation and to assist the engine as commanded by the hybrid controller when accelerating under workload conditions.
In tests comparing the standard PC200LC-8 hydraulic excavator to the Hybrid PC200LC-8, the hybrid model reduced fuel consumption by approximately 25-40%, depending on the application.
During the demonstration session of the program, skilled operators, one running the new hybrid machine and the other running a standard version of the same machine went head to head to illustrate the fuel savings potential. The standard machine was operating at a fuel consumption rate of 4.1 gallons per hour compared to the hybrid’s consumption rate of 3.2 gallons per hour. This is around a 47% fuel savings. Both machines were equipped with furl monitoring gauges.
The Hybrid PC200LC-8 is powered by the turbocharged and air-to-air after-cooled Komatsu SAA4D107E-1 which provides138HP. With an operating weight of 43,643 to 47,260 pounds, the Hybrid PC200LC-8 has a bucket capacity of 0.66 – 1.57 yd3. The Hybrid PC200LC- has the same working forces and performance levels of the conventional PC200LC-8.
The innovative cab design assures operator comfort because the viscous cab damper mounts reduce vibration. A 7” LCD monitor provides easy-to-read gauges and onboard diagnostics as well as displaying the rear-view monitoring system for viewing the work area to rear of the machine.
KOMTRAX on board
The Hybrid PC200LC-8 is also equipped with the latest KOMTRAX technology which sends machine operating information to a secure website utilizing wireless technology. Data such as operating hours, fuel consumption, machine location and machine utilization are relayed to the web application for analysis. The KOMTRAX fleet monitoring system increases machine availability, reduces the risk of machine theft and provides a wealth of other information to drive business efficiency.
The Hybrid PC200LC-8 excavator was introduced to the Japanese market in June 2008, and has been successful in reducing fuel consumption. In addition, Komatsu introduced the Hybrid to the Chinese market in August this year.
Komatsu Hybrid Technology
Komatsu Harmony is fundamental in matching the diesel/electric Hybrid system to the hydraulic requirements to provide high productivity with low fuel consumption. The Hybrid controller synchronizes the conventional engine and hydraulic pumps with electric assist to provide a unique operational experience. The more the operator uses the Hybrid technology by swinging and regenerating energy, the greater is the fuel consumption benefit
Hybrid Excavator Energy Flow
The hybrid system drives the upper structure with an electric motor. The electric motor is also used to regenerate energy as the upper structure slows down. Fuel consumption is improved by the ability to use the regenerated energy to assist during high power demands allowing the engine to run at an optimum speed for high efficiency.
Ultra Capacitor for Energy Storage
In construction equipment, the energy demand is high and occurs in a short amount of time. Combined with a high frequency of demand, the electrical energy requirements to operate construction equipment cannot be met with current battery technology.
The “Komatsu Hybrid System” uses an “Ultra Capacitor” to instantaneously store and give off electrical energy efficiently. This capacitor charges and discharges at a much faster rate than the slower chemical reactions that take place in batteries. The instantaneous charging and dis- charging characteristics of a capacitor match the high-energy demand and frequent cycles needed by an excavator.
The Hybrid PC200LC-8 uses an electric swing motor that rotates the upper structure and recovers energy during swing braking. A special housing, which circulates cooling water and lubricating oil, further enhances durability.
Inverter (Converter) and Ultra Capacitor
The inverter receives AC energy and converts it to DC energy from two sources:
1. Recovered energy from the swing motor/generator
2. Charging power from the engine’s generator/motor
The converted DC energy from these two sources is quickly stored in the Ultra Capacitor. The stored DC energy is then quickly released and converted to AC to power the swing motor and to assist the engine RPM. A special housing allows cooling water to circulate further enhancing durability.
The generator motor is built-in between the engine and hydraulic pump for effective power transmission to the hydraulic pumps. The generator can charge the capacitor during periods when no work equipment or travel operations are used. The generator motor also receives power from the capacitor for engine assist, as commanded by the Hybrid controller.
The machine monitor panel includes a “Hybrid Operation Monitor” screen to display energy flow as the machine operates. The monitor screen can be changed to display status of capacitor charging and discharging and engine assist by the generator/motor as energy flow. The Hybrid controller manages energy flow making it seamless for the operator.
The work equipment is operated hydraulically by energy generated by the engine as in the conventional equipment (red arrows). Swing is driven by electrical energy from the capacitor and generator (yellow arrows).
Energy generated during swing deceleration is regenerated and is stored in the capacitor (green arrows). Some of the regenerated energy assists the engine through the generator/motor and assists work equipment operation.
This article will be appearing in the December issues of all ACP magazines.